JP2006178238A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image scanner equipped with a light source capable of preventing black stripes (shadow) caused at the end of a stuck document without making a circuit or control complicated nor making an illuminator expensive. <P>SOLUTION: The light source for illuminating a document placed on a contact glass on which the document is placed is constituted of a plurality of light emitting diodes arranged on both sides so as to attain the same illuminance at the position of the optical axis of an optical system in a main scanning direction being the reading direction of a line sensor for reading the image of the document illuminated by the light source, and the light emitting diodes are mounted on a light emitting diode mounting plate constituted to move in a subscanning direction orthogonal to the main scanning direction, and also constituted to move in the main scanning direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading apparatus in a copying machine, a facsimile, or the like. The present invention relates to an image reading apparatus.

  As an optical system for reading a document used in a reading device in a copying machine or a facsimile, for example, a reflection mirror for reflecting and sending a document image can be provided under a contact glass on which the document is placed. And a reflecting mirror for forming an image of a document sent from the reflecting mirror on the first moving body on a line sensor using a CCD or the like via a lens. The optical path length from the document to the lens is made constant, and the second moving body that can move at half speed in the moving direction of the first moving body, or directly under the contact glass For example, a line sensor using a CCD or the like is arranged for reading.

  As a light source for illuminating the document placed on the contact glass surface, a rod-shaped light source such as a halogen lamp or a xenon lamp, or a light emitting diode (hereinafter abbreviated as LED) as disclosed in Patent Document 1. A plurality of point light sources are arranged in parallel to the arrangement direction of the sensors such as CCDs in the line sensor for image reading (hereinafter, this direction is referred to as a main scanning direction), and a light amount adjustment circuit is provided for each LED. A structure in which illumination is performed while eliminating unevenness in the amount of light is known.

JP 2002-314760 A

  However, in a light source using a rod-shaped light source such as a halogen lamp or a xenon lamp, or a point light source such as an LED as disclosed in Patent Document 1, for example, as shown in FIG. In the case of a document 15 having a thickness such that another document 17 is pasted on the reference document 16 placed on the document, the end 18 of the other document 17 is positioned near the optical axis 10 of the reading optical system. Then, the illumination light 13 from the LED 11 cannot illuminate the end 18, and black streaks (shadows) are generated at the end of the other document 17 in the read image.

  Further, in the illumination means disclosed in Patent Document 1, since the light amount adjustment circuit is provided in each LED so as to eliminate the uneven light amount, the circuit and control are complicated.

  Therefore, in the present invention, black streaks (shadows) generated at the edges of the laminated document as shown in FIG. 6 are prevented without complicating the circuit and control, and without increasing the cost of the illumination device. It is an object to provide an image reading apparatus provided with such a light source.

In order to solve the above problems, an image reading apparatus according to the present invention provides:
In an image reading apparatus comprising: a light source that illuminates an original placed on a contact glass on which an original is placed; and an optical system that forms an image of the original illuminated by the light source on a reading element using a line sensor.
The light source is provided on both sides of the optical system optical axis in the main scanning direction which is a reading direction of the line sensor, and is mounted on a light emitting diode mounting plate configured to be movable in the sub scanning direction orthogonal to the main scanning direction. It is comprised of a plurality of light emitting diodes that are mounted and configured to be movable in the main scanning direction.

  Thus, the light emitting diode is used as a light source, and the light emitting diode is provided on both sides of the optical system optical axis in the contact glass with the optical system optical axis in between, so that the end portion in the pasted document as described above It is possible to prevent the occurrence of black streaks (shadows). In addition, by being configured to be movable in the main scanning direction and sub-scanning direction, the illuminance at the optical axis of the optical system can be easily adjusted, and uniform illuminance can be achieved without complicating the drive circuit and control circuit as in the prior art. Can be easily obtained. Furthermore, in order to obtain the same illuminance as when the light emitting diodes arranged on both sides of the optical system optical axis are arranged in a line parallel to the optical system optical axis, the light emitting diodes are simply dispersed on both sides of the optical system optical axis. It is possible to provide an image reading apparatus that can obtain a good reading result without increasing the price.

  And the said light emitting diode can illuminate the optical system optical-axis position uniformly by arrange | positioning in a zigzag shape on both sides of the said optical system optical axis.

  The light emitting diode mounting plate is divided into a plurality of parts in the main scanning direction, each of which is mounted with a plurality of light emitting diodes, and individually movable in the sub scanning direction. Adjustment in the main scanning direction and sub-scanning direction is possible, and adjustment can be performed more easily.

  As described above, according to the present invention, it is possible to prevent the occurrence of black streaks (shadows) generated at the edges of the laminated originals as described above without increasing the cost of the light source. It is possible to provide an image reading apparatus capable of easily adjusting the illuminance on the optical axis of the optical system without complicating the control circuit and easily obtaining uniform illuminance.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a perspective view of Embodiment 1 of a light source in an image reading apparatus according to the present invention, FIG. 2 is an exploded view of components constituting the light source of Embodiment 1, and FIG. 3 is a diagram of a light source in the image reading apparatus according to the present invention. FIG. 4 is a perspective view of a light source in a third embodiment of the light source in the image reading apparatus according to the present invention. FIG. 5 is a diagram showing a state of document illumination using the light source in the image reading apparatus according to the present invention. It is.

  An outline of the image reading apparatus will be described with reference to FIG. 5 showing a state of document illumination using a light source in the image reading apparatus of the present invention. The image reading apparatus according to the present invention is a light in an optical system that forms an image of a document directly or via a lens or the like on a line sensor composed of a CCD (not shown) for converting the document image into an image signal. Light-emitting diodes (hereinafter abbreviated as LEDs) 11 are arranged on both sides of the axis 10 in parallel with the main scanning direction, which is the scanning direction of a line sensor (not shown), and contacts 12 and 13 from both sides of the optical axis 10. The document 15 placed on the glass 14 can be illuminated.

  By illuminating from both sides of the optical axis 10 in this way, a document having a thickness as if a single document is formed by pasting another document 17 on the reference document 16 as shown in FIG. 15, since the irradiation light 12 is also applied to the end portion 18 side of the other document 17, it is possible to prevent the end portion 18 of the other document 17 from being irradiated with illumination light and becoming a black line as in the prior art.

  The light emitting diodes 11 arranged on both sides of the optical axis 10 of the optical system are arranged so as to have the same illuminance at the position of the optical axis 10 in the contact glass 14 across the optical axis 10 of the optical system. In order to obtain the same illuminance as when arranged in a row in parallel with each other, it is only necessary to disperse and arrange a row of light emitting diodes on both sides of the optical axis 10, and the drive circuit and the control circuit are changed or increased. Since there is no need, it is possible to provide an image reading apparatus that can obtain a good reading result without increasing the price.

  By configuring the light emitting diode 11 so as to be movable in the main scanning direction and the sub-scanning direction orthogonal to the main scanning direction, the illuminance on the optical axis 10 can be easily adjusted. Uniform illumination can be easily obtained without complicating the circuit.

  FIG. 1 is a perspective view of Example 1 of a light source unit in an image reading apparatus according to the present invention configured based on such a concept. FIG. 2 is an exploded view of components constituting the light source unit 20 of Example 1. In FIG. 1 and FIG. 2, the same parts as those described with reference to FIG.

Reference numeral 10 denotes an optical axis of an optical system arranged in the image reading apparatus. As described above, the optical axis is directly or via a lens or the like to a line sensor composed of a CCD (not shown) for reading a document of the image reading apparatus. This is the optical axis in the optical system for forming the original image. Reference _numerals 11 ₁ and 11 ₂ denote illumination LEDs as light sources provided on both sides of the optical axis 10, and 21 denotes a window (slit) provided on the slit adjusting plate 22. The center of the window 21 is the optical axis 10. Is consistent with The image of the original illuminated by the illumination LEDs provided on both sides of the optical axis 10 passes through this window 21 and forms an image directly on a line sensor (not shown) or is installed under this window 21. An image is sent to a line sensor (not shown) via the reflecting mirror and lens.

Reference numerals 23 ₁ and 23 ₂ denote light-emitting diode mounting plates on which the LEDs 11 ₁ and 11 ₂ as light sources are mounted. The LEDs 11 ₁ and 11 ₂ are mounted on the slit adjusting plate 22 described above, and screws 24 ₁ are mounted. 24 ₂ , 24 ₃ , 24 ₄ , the position on the slit adjusting plate 22 can be adjusted. The light emitting diode mounting plates are formed on both sides of the window, and constitute first and second light emitting diode mounting plates. And Figure 25 is a position adjusting pin ₂₆ 1, 26 ₂ is implanted elongated hole ₂₇ 1 in the slit adjusting plate 22, 27 ₂ is fitted, a sub-scanning direction in the slit adjustment plate 22 by screws ₂₈ 1, 28 ₂ It is a base that can be fixed while adjusting the position of the head.

Of these, as shown in FIG. 2, in addition to the position adjustment pins 26 ₁ and 26 ₂ described above, when the window 21 provided on the slit adjustment plate 22 moves left and right, the original image is lined on the base 25. Mounted in the opening 29 larger than the window 21 so as to be sent to the sensor, the tap holes 30 ₁ and 30 ₂ for screwing the screws 28 ₁ and 28 ₂ for fixing the slit adjusting plate 22, and the slit adjusting plate 22. Holes 31 ₁ , 31 ₂ , 31 ₃ , 31 ₄ , _first holes for releasing the tips of screws 24 ₁ , 24 ₂ , 24 ₃ , 24 ₄ for fixing the first and second light emitting diode mounting plates 23 ₁ , 23 ₂ , screw ₃₂ 1, 32 long hole ₃₃ 1 in which the sub-scanning direction is the longitudinal direction in order to release the _second tip for fixing the LED 11 _1, 11 ₂ which is fixed to the second upper light emitting diode mounting plate ₂₃ 1, 23 _2, 3 _2, and the like are provided.

In addition to the window 21 and the long holes 27 ₁ , 27 ₂ , the slit adjusting plate 22 has the LEDs 11 mounted on the first and second light emitting diode mounting plates 23 ₁ , 23 ₂ as in the case of the base 25. _1, 11 ₂ screw ₃₂ 1 for fixing the 32 _second long holes ₃₄ 1 and the sub-scanning direction is the longitudinal direction in order to release the tip, 34 _2, and the first and second light emitting diode mounting plate ₂₃ 1, 23 ₂ are provided with tap holes 35 ₁ , 35 ₂ , 35 ₃ , and 35 ₄ for screwing screws 24 ₁ , 24 ₂ , 24 ₃ , and 24 ₄ to fix the screws ₂ , and further, first and second light emitting diode mounting plates 23 _1. , the 23 _2, LED 11 _1, 11 tap hole ₃₆ 1 the screw ₃₂ 1, 32 _{2 2} are fixed is screwed, 36 _2, the LED 11 _1, 11 _2, the position adjustment by the screw ₃₂ 1, 32 ₂ Main scan direction for Longitudinal and the long holes ₃₇ 1, 37 _2, and, LED 11 _1, 11 position adjusting pin holes ₄₀ 1 of _2, 40 ₂ are provided. Note that arrows indicated by 38 and 39 in FIG. 1 indicate the main scanning direction (38) and the sub-scanning direction (39) at the time of reading a document image.

The light source unit 20 configured as described above is provided under the contact glass 14 on which a document to be copied or transmitted is placed as shown in FIG. 5, and a blank document is placed on the contact glass 14. The reflected light of the white original irradiated by the left and right LEDs 11 ₁ and 11 ₂ is received by a line sensor (not shown) and reaches the position of the optical axis 10 as follows (that is, to a line sensor (not shown)). Adjust so that the amount of light reached reaches even.

First, placing the blank original on the contact glass 14 as described above, illuminates the screws 28 _1, 28 ₂ drawing right LED 11 _2, for example, loosening the fixing the slit adjusting plate 22 shown in FIG. 1, the slits The adjustment plate 22 is moved along the position adjustment pins 26 ₁ and 26 ₂ in the sub-scanning direction indicated by 39, the light amount is detected by a line sensor (not shown), and the screw is positioned at 90% of the maximum irradiation light amount. It is fixed by 28 ₁ and 28 ₂ .

Then light the LED 11 ₁ a diagram left, the first light emitting diode mounting plate 23 ₁ detects the amount by the line sensor (not shown) is moved in the sub-scanning direction indicated by 39, a contact glass 14 on the surfaces of The position which becomes 90% of the maximum irradiation light amount at the position of the optical axis 10 is searched and fixed with screws 24 ₁ and 24 ₂ .

Thereafter, the light distribution in the main scanning direction indicated by 38 is confirmed, and when unevenness in the amount of light such as ripple occurs, the LED 11 ₁ , 11 _{2 with} unevenness in the amount of light has light in the position adjusting pin holes 40 ₁ and 40 ₂ . The adjustment pins are inserted and individually moved in the main scanning direction indicated by 38, and are fixed using screws 32 ₁ and 32 ₂ at positions where unevenness in the amount of light does not occur.

Then, the left and right LEDs 11 ₁ and 11 ₂ are alternately turned on again to check whether the optical axis 10 on the surface of the contact glass 14 is 90% of the maximum irradiation light amount. Finally, both the LEDs 11 ₁ and 11 ₂ are all turned on. When the illumination light quantity at the optical axis 10 on the surface of the contact glass 14 is not less than a predetermined threshold value, the adjustment is finished. However, if this value is less than or equal to the threshold value, the first and second light emitting diode mounting plates 23 ₁ and 23 ₂ are adjusted again, and the irradiation light quantity is set to be equal to or greater than the threshold value, and the process ends.

In this way, by equalizing the amount of light reaching the optical axis 10 (that is, the amount of light reaching a line sensor not shown) by the left and right LEDs 11 ₁ , 11 ₂ , each of the individual LEDs 11 ₁ , 11 ₂ is obtained. The document 15 placed on the surface of the contact glass 14 can be irradiated with a uniform light amount without providing a circuit for controlling the light amount.

FIG. 3 is a perspective view of the light source unit in the image reading apparatus according to the second embodiment of the present invention. In the first embodiment, the LEDs 11 ₁ and 11 ₂ provided on the left and right are individually positioned in the main scanning direction. Although it is configured to be adjustable, in the second embodiment, the entire light emitting diodes arranged on the left and right sides of the optical axis 10 of the optical system can be moved in the main scanning direction, so that the adjustment work can be simplified. Is.

In the figure, the same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and 10 is constituted by a CCD or the like (not shown) for reading a document of the image reading apparatus as described above. to have been the line sensor, the optical axis in an optical system for forming an original image via a direct or lens, 50 is a light source unit example 2, 51 _1, 51 ₂ provided on both sides of the optical axis 10 in lighting LED, 52 is provided in the slit adjustment plate 53 in order to send to the LED 51 _1, 51 ₂ line sensors (not shown) an image of the illuminated document in the window, under the window 52 as described above In this case, an image is sent to the line sensor via a lens or the like by directly installing a line sensor or a reflecting mirror.

54 _1, 54 ₂ are placed a LED 51 _1, 51 ₂ on the slit adjustment plate 53, the position of the slit adjustment plate 53 by screws _{55 1,} 55 _{2, 55} 3, 55 _4, 55 5, 55 ₆ first and second light emitting diode mounting plate which is adapted to be adjusted to, 25 adjust the position pin ₂₆ 1, 26 ₂ is erected long holes ₅₆ 1 in the slit adjustment plate 53, 56 ₂ is fitted, This is a base that can be fixed while adjusting the position of the slit adjustment plate 53 in the sub-scanning direction with the screws 28 ₁ and 28 ₂ .

Of these, although not shown on the base 25, when the window 52 provided on the slit adjustment plate 53 moves to the left and right in addition to the position adjustment pins 26 ₁ and 26 ₂ , the original image is used as a line sensor. Okuridaseru opening and which is largely opened from window 52 as the tap hole for screwing the screws 28 _1, 28 ₂ for fixing the slit adjusting plate 53, the first is mounted on the slit adjusting plate 53, a second light emitting screw _{57 1,} 57 _2, for fixing the diode mounting plate ₅₄ 1, 54 ₂ 57 3, 57 ₄ of escape front end hole, the 1, LED 51 is fixed to the second upper light emitting diode mounting plate ₅₄ 1, 54 _{2 1,} 51 ₂ screw 55 1 for fixing _the, 55 long hole or the like in the sub-scanning direction is the longitudinal direction in order to release the _second tip is provided.

Further the slit adjustment plate 53, the window 52 described above, in addition to the long holes ₅₆ 1, 56 _2, as in the case of the base 25, for mounting a first, _two second light-emitting diode mounting plate ₅₄ 1, 54 LED 51 _1, 51 ₂ screw ₅₅ 1 for fixing _the, 55 _{2, 55} 3, 55 _4, 55 5, 55 ₆ long hole was in the sub-scanning direction is the longitudinal direction in order to release the tip, and first and second light-emitting screw ₅₇ 1 for fixing the diode mounting plate ₅₄ 1, 54 _2, 57 _2, 57 3, 57 ₄ screwed to the tap hole, and a light emitting diode ₅₁ 1, 51 ₂ so that the can moves in the main scanning direction 38, the first , 1 second light emitting diode mounting plate _54, 54 _two-position adjustment pin ₅₉ 1 that is implanted _into, 59 _2, 59 3, 59 ₄ elongated holes 58 ₁ provided in the main scanning direction as the longitudinal direction is fitted , ₅₈ 2, 5 _3, 58 _4, further first, second to the light emitting diode mounting plate ₅₄ 1, 54 _2, LED 51 _1, 51 ₂ screw ₅₅ 1 for fixing _the, 55 _{2, 55} 3, 55 _4, 55 5, 55 A tap hole to which ₆ is screwed is provided. Note that arrows indicated by 38 and 39 indicate the main scanning direction (38) and the sub-scanning direction (39) when the document image is read.

The light source unit 50 configured as described above is provided under the contact glass 14 on which a document to be copied or transmitted is placed as shown in FIG. 5, and a blank document is placed on the contact glass 14. , the left and right LED 51 _1, 51 reflected light of the white original by _2, to receive the line sensor (not shown) amount (i.e. a line sensor (not shown) reaching as follows to the position of the optical axis 10 Adjust so that the amount of light reached reaches even.

First, placing the blank original on the contact glass 14 as described above, it illuminates the screws 28 _1, 28 ₂ LED51 ₂ on the figure right example by loosening the fixing the slit adjusting plate 53 shown in FIG. 3, the slits The adjustment plate 53 is moved along the position adjustment pins 26 ₁ , 26 ₂ in the sub-scanning direction indicated by 39, the light amount is detected by a line sensor (not shown), and the screw is positioned at a position where it becomes 90% of the maximum irradiation light amount. It is fixed by 28 ₁ and 28 ₂ .

Then light the LED 51 ₁ a diagram left, the first light emitting diode mounting plate 54 ₁ detects the amount by the line sensor (not shown) is moved in the sub-scanning direction indicated by 39, a contact glass 14 on the surfaces of A position that is 90% of the maximum irradiation light amount is searched for at the position of the optical axis 10 and fixed by screws 54 ₁ and 54 ₂ .

Then, check the main scanning direction of the light distribution shown in 38, when the light intensity variation of the ripple or the like is generated, the screw ₅₅ 1 in LED 51 _1, 51 ₂ with a light intensity _variation, 55 _2, 55 3, 55 _{4, 55} 5, 55 ₆ is moved in the main scanning direction indicated by 38, the screw ₅₅ 1 at a position where the light amount unevenness does not _occur, 55 _{2, 55} 3, 55 _4, 55 5, fixed with 55 ₆ .

Then, the left and right LEDs 51 ₁ and 51 ₂ are alternately turned on again to check whether the optical axis 10 on the surface of the contact glass 14 is 90% of the maximum irradiation light amount. Finally, both the LEDs 51 ₁ and 51 ₂ are all turned on. When the illumination light quantity at the optical axis 10 on the surface of the contact glass 14 is not less than a predetermined threshold value, the adjustment is finished. However, if this value is below a threshold, the first and adjusts the second light emitting diode mounting plate 54 _1, 54 ₂ again, and ends by setting that the irradiation light quantity is equal to or greater than the threshold value.

In this way, the amount of light reaching the optical axis 10 by the left and right LEDs 51 ₁ and 51 ₂ (that is, the amount of light reaching a line sensor (not shown)) is equalized, thereby controlling the amount of light for each of the LEDs 51 ₁ and 51 _2. Therefore, it is possible to irradiate the document 15 placed on the surface of the contact glass 14 with a uniform amount of light.

Figure 4 is a perspective view of a third embodiment of the light source unit in the image reading apparatus to the present invention, in the embodiment 2 described above, LED 51 _1, 51 ₂ so that the entire movable in a main scanning direction which is provided on the left and right The adjustment work has been simplified, but in case that it is difficult to adjust the amount of light in the main scanning direction, the LED is made into a block and a plurality of light emitting diode mounting plates are provided on each of the left and right sides so that the position can be adjusted for each block. Is.

In the figure, the same components as those in the first and second embodiments shown in FIGS. 1 and 3 are denoted by the same reference numerals, and 10 is a diagram for reading a document of the image reading apparatus as described above. An optical axis in an optical system for forming an original image directly or via a lens or the like on a line sensor constituted by a non-CCD or the like, 60 is a light source unit of Example 3, 61 ₁ , 61 ₂ , 61 ₃ , 61 ₄ , 61 ₅ , 61 ₆ are illumination LEDs provided on both sides of the optical axis 10, and 62 is an image of a document illuminated by the LEDs 61 ₁ , 61 ₂ , 61 ₃ , 61 ₄ , 61 ₅ , 61 _6. This is a window provided on the slit adjustment plate 63 for sending to a line sensor that is not, and as described above, a line sensor is directly installed under the window 62, or a reflecting mirror is installed via a lens or the like. Image to line sensor Will be sent.

64 ₁ and 64 ₂ are LEDs 61 ₁ , 61 ₂ , 61 ₃ , 61 ₄ , 61 ₅ , and _{6 6} mounted on the slit adjusting plate 63, and positions on the slit adjusting plate 63 with screws 65 _{1 to} 65 _12. The first and second light emitting diode mounting plates 25 that can be adjusted, the position adjusting pins 26 ₁ and 26 ₂ are planted, and the long holes 66 ₁ and 66 ₂ in the slit adjusting plate 63 are inserted, This is a base that can be fixed while adjusting the position of the slit adjustment plate 63 in the sub-scanning direction with the screws 28 ₁ and 28 ₂ .

Of these, although not shown in the base 25, when the window 62 provided on the slit adjustment plate 63 moves to the left and right in addition to the position adjustment pins 26 ₁ and 26 ₂ , the original image is used as a line sensor. Okuridaseru opening and which is largely opened from window 62 as the tap hole for screwing the screws 28 _1, 28 ₂ for fixing the slit adjusting plate 63, the first is mounted on the slit adjusting plate 63, a second light emitting screw ₆₇ 1 for fixing the diode mounting plate ₆₄ 1, 64 _2, 67 _2, 67 3, 67 ₄ of escape front end hole, first, is fixed to the second light emitting diode mounting plate ₆₄ 1, 64 ₂ on LED61 _{1, 61 2,} 61 _3, 61 _4, 61 5, 61 ₆ long hole or the like in the sub-scanning direction is the longitudinal direction in order to release the tip of the screw _{65 1-65 12} for fixing the can is provided.

Further the slit adjusting plate 63, the above-described window 62, in addition to the long holes ₆₆ 1, 66 _2, as in the case of the base 25, for mounting the first, the second light emitting diode mounting plate ₆₄ 1, 64 ₂ LED 61 ₁ , 61 ₂ , 61 ₃ , 61 ₄ , 61 ₅ , 61 ₆ , a long hole whose longitudinal direction is the sub-scanning direction for releasing the tips of the screws 65 _{1 to} 65 ₁₂ , and the first and second light emission diode mounting plate ₆₄ 1, 64 ₂ screw ₆₇ 1 for fixing _the, 67 _2, 67 3, 67 ₄ screwed to the tap hole, and the first, second to the light emitting diode mounting plate ₆₄ 1, 64 _2, LED 61 _1, 61 ₂ screw _{65 1-65 12} fixed and a tap hole for screwing is provided.

The light source unit 60 configured as described above is provided under the contact glass 14 on which a document to be copied or transmitted is placed as shown in FIG. 5, and a blank document is placed on the contact glass 14. The reflected light of the white document irradiated by the left and right LEDs 61 ₁ and 61 ₂ is received by a line sensor (not shown) and reaches the position of the optical axis 10 as described above (ie, to a line sensor (not shown)). However, this operation is performed for each block of the light emitting diodes 61 ₁ , 61 ₂ , 61 ₃ , 61 ₄ , 61 ₅ , and _{6 6} , and is completely the same as in the first and second embodiments. Since it is the same, description is abbreviate | omitted.

  As described above, according to the present invention, a light emitting diode is used as a light source, and the light emitting diode is provided on both sides of the optical system optical axis in the contact glass with the optical system optical axis in between. Thus, it is possible to prevent the occurrence of black streaks (shadows) generated at the edge of the pasted original as described above. In addition, by being configured to be movable in the main scanning direction and sub-scanning direction, the illuminance at the optical axis of the optical system can be easily adjusted, and uniform illuminance can be achieved without complicating the drive circuit and control circuit as in the prior art. Can be easily obtained. Furthermore, in order to obtain the same illuminance as when the light emitting diodes arranged on both sides of the optical system optical axis are arranged in a line parallel to the optical system optical axis, the light emitting diodes are simply dispersed on both sides of the optical system optical axis. It is possible to provide an image reading apparatus that can obtain a good reading result without increasing the price.

  According to the present invention, there is provided an image reading apparatus capable of preventing the occurrence of black streaks (shadows) generated at the edge of a laminated document without complicating the circuit and control and without increasing the cost of the light source. Can produce a great effect.

It is a perspective view of Example 1 of the light source in the image reading apparatus according to the present invention. FIG. 2 is an exploded view of components constituting the light source of Example 1. It is a perspective view of Example 2 of the light source in the image reading apparatus which becomes this invention. It is a perspective view of Example 3 of the light source in the image reading apparatus which becomes this invention. It is the figure which showed the state of the original illumination using the light source in the image reading apparatus which becomes this invention. It is the figure which showed the state of the original illumination using the light source in the image reading apparatus which becomes this invention.

Explanation of symbols

10 Optical axis 11, 11 ₁ , 11 ₂ LED
12, 13 Illumination light 14 Contact glass 15 Document 16 Reference document 17 Other document 18 Other document edge 20 Light source unit 21 Window 22 Slit adjustment plate 23 ₁ First LED mounting plate 23 ₂ Second LED mounting plates _{24 1,} 24 _2, 24 3, 24 ₄ screw 25 base plate ₂₆ 1, 26 ₂ alignment pins ₂₇ 1, 27 ₂ elongated holes ₂₈ 1, 28 ₂ screws 29 openings ₃₀ 1, 30 ₂ tap holes ₃₁ 1, 31 _{2, 31} 3, 31 ₄ holes ₃₂ 1 to release the tip of the screw, 32 ₂ emission screws ₃₃ 1 diode fixing the, 33 ₂ elongated holes ₃₄ 1 to release the tip of the screw, 34 ₂ elongated holes 35 ₁ to release the leading end of the screw , 35 ₂ , 35 ₃ , _{3 4 4} Tap holes 36 ₁ , 36 ₂ Tap holes 37 ₁ for screwing screws for fixing the LEDs 11 ₁ , 11 ₂ . 37 ₂ position adjusting long hole 38 main scanning direction 39 sub scanning direction 40 ₁ , 40 ₂ position adjusting pin hole

Claims (3)

In an image reading apparatus comprising: a light source that illuminates an original placed on a contact glass on which an original is placed; and an optical system that forms an image of the original illuminated by the light source on a reading element using a line sensor.
The light source is provided on both sides of the optical system optical axis in the main scanning direction which is a reading direction of the line sensor, and is mounted on a light emitting diode mounting plate configured to be movable in the sub scanning direction orthogonal to the main scanning direction. An image reading apparatus comprising a plurality of light emitting diodes mounted and configured to be movable in the main scanning direction.   The image reading apparatus according to claim 1, wherein the light emitting diodes are arranged in a zigzag pattern across the optical axis of the optical system.   3. The light emitting diode mounting plate is divided into a plurality of parts in the main scanning direction, each of which is mounted with a plurality of light emitting diodes, and individually movable in the sub scanning direction. The image reading apparatus described in 1.

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